Light emitting devices with light emitting diode chip are generally formed by mounting light emitting diode chips on packages of various forms according to application purposes.
One of the light emitting devices having a protection element is disclosed in JP 2007-280983 A (Patent Literature 1). FIG. 14 is a perspective view showing the conventional light emitting device disclosed in Patent Literature 1.
In FIG. 14, a package 1 has an opening 3 for a light emitting element 2 and an opening 4 for a protection element in one side surface. The light emitting element 2 is mounted in a recess section 5 which forms the opening 3. The protection element (not shown) is mounted in a recess section 6 which forms the opening 4.
The opening 4 is formed independently of the opening 3 of the recess section 5 which has the light emitting element 2 mounted therein. In short, the package 1 functions as a wall enclosing the opening 4 to define a protection element mounting region. Such configuration allows reliable separation of the light emitting element 2 and the protection element, and therefore it becomes possible to prevent the protection element from being exposed to the light emitted from the light emitting element 2. As a result, deterioration in luminous efficiency can be suppressed and a high power light emitting device can be implemented.
Another light emitting device having a protection element is disclosed in WO 2007/069399 A (Patent Literature 2). FIG. 15 is a plan view of the conventional light emitting device disclosed in Patent Literature 2.
In FIG. 15, the light emitting device 11 has a light emitting diode 13 mounted on a heat radiating member 12, and has a protection element (Zener diode) 15 mounted on a metal tab 14 whose upper surface is lower than that of the heat radiating member 12. This prevents the protection element 15 from blocking the light from the light emitting diode 13, and thereby suppresses deterioration in luminous efficiency of the light emitting diode 13.
Further, one of the two electrodes of the light emitting diode 13 is electrically connected to a first inner lead 16, while the other electrode of the light emitting diode 13 is electrically connected to a second inner lead 17. An electrode on an upper surface of the protection element 15 is electrically connected to the first inner lead 16, while an electrode on a lower surface of the protection element 15 is electrically connected to the metal tab 14.
These conventional light emitting devices having protection elements have following problems.
In the conventional light emitting device described in the Patent Literature 1, the opening 4 for the protection element is provided independently of the opening 3 for the light emitting element 2 and these openings are arranged in the longitudinal direction of the package 1 made of resin. This causes a problem of increased longitudinal length of the package 1. Further, provision of a plurality of openings 3, 4 in the package 1 tends to complicate the manufacturing process of the package 1, which in turn causes increased manufacturing costs of the light emitting element packages.
As shown in FIG. 14, the center of the package 1 is not necessarily the center of the opening 3 for the light emitting element 2, which causes a problem of displaced light emitting axis.
The light emitting device described in the Patent Literature 2 has the metal tab 14 which is formed for mounting the protection element 15 and which has an upper surface lower than that of the heat radiating member 12 for mounting the light emitting diode 13. The metal tab 14 and the second inner lead 17 are connected with a wire so as to electrically connect the electrode on the lower surface of the protection element 15 and the second inner lead 17 to establish parallel connection between the light emitting diode 13 and the protection element 15.
Necessity of forming the metal tab 14 and connecting the metal tab 14 to the second inner lead 17 with a wire causes a problem of complicated manufacture process of packages and hence increased manufacturing costs of the light emitting device.